1. Field of the Invention
The present invention relates to projectiles, such as arrows usable with large game bows, having heads with a plurality of expandable blades.
2. Description of the Prior Art
Conventional arrows have arrowheads with one or more fixed blades. The cutting ability of these arrows is limited, which often results in a superficial wound or a wound causing the hunted game to slowly bleed to death or suffer. Also, conventional arrows have a tendency to pass through the game or other target without expending all their kinetic energy, resulting in lost arrows and lost game. The term "game" refers to wild animals, fowl and fish.
Advancements in bow technology and the introduction of graphite or carbon fiber arrows have dramatically increased the speed at which it is possible to deliver an arrow. Conventional arrowheads with protruding blades become inaccurate at these higher speeds because of the effects of air on the exposed blades. This leads to inaccurate placement of the arrow and an increase in unrecovered and wounded animals. In an effort to make these "winged" arrowheads more accurate at higher speed, manufacturers have been reducing the cutting diameter of the average conventional broadhead. This has resulted in a greater percentage of arrows that pass through game completely and continue on for some distance. The result is that a lot of the additional potential cutting energy generated by the new high performance bows is not efficiently utilized for cutting. There is a need for an arrowhead that flies accurately at high speed yet delivers at the same time a large cutting diameter to dispatch game cleanly and quickly and take advantage of the increased energy of today's bows.
Prior hunting arrowheads have been provided with deployable blades. For example, the Pucketts Bloodtrailer U.S. Pat. No. 5,112,063 and the Delucia U.S. Pat. No. 4,976,443 describe arrowheads which are deployed by engagement of a plunger mechanism. These heads do not penetrate game well because of the mechanics of blade opening and the necessary blunt profile of the plunger tip and the accommodating bodies. They are structurally weaker because of the hollow body design. A further objection to these heads is that they don't provide any additionally cut size relative to conventional broadheads. Necessary lightweight construction requires that most hunting arrowheads are made of aluminum material, which is malleable. The blades on these designs use the body of the arrowhead as a stop, but the blades readily cut through the malleable aluminum of the arrowhead body on impact with something hard such as bone. This leads to malfunction of the arrowhead on game and more lost game, and it renders the arrowhead useless.
Prior arrowheads have been provided, with movable cutting blade structure that cooperates with one or more fixed blades to cut game or a target. For example, B. H. Steinbacher, U.S. Pat. No. 2,568,417, discloses an arrowhead assembly having fixed blades and a pair of pivoting blades located between the fixed blades. The pivoting blades move in a rearward direction to an open position when the arrowhead enters the game or target. Additional hunting arrows having expandable cutting blades are shown by E. P. Cox in U.S. Pat. No. 3,738,657 and R. S. Vocal in U.S. Pat. No. 4,615,529.
Another representative patent is by Johnson, U.S. Pat. No. 5,090,709, issued on Feb. 25, 1992, entitled "Arrowhead With Extendable Blades," the same inventor as this patent application.
The present invention also enhances the Johnson '709 patent. What is provided is an aerodynamically designed retractable-blade arrowhead with offset blades and a sturdier backstop made of steel or like material that does not significantly increase the overall weight of the arrowhead, and that is, further, replaceable so that the arrowhead may be reusable. A backstop that will stop rearward movement of the blades even when striking the toughest bones is provided to prevent the blades from pivoting past the desired stopping points so that the cutting diameter does not become reduced.
All other deployable-blade arrowheads have blades held in slots that form a plane that contains the centerline of the arrowhead. In this configuration the slot depth is limited by the center axis of the arrowhead and it is not possible to contain three or more blades generally within the arrowhead body (at the same distance back from the tip) without significantly increasing the arrowhead width or excessive structural weakening. Arrowheads with stationary offset blades are described in Kosbab, U.S. Pat. No. 4,210,330, but there is no known deployable-blade arrowhead with blades held in slots which are offset relative to the central axis of the arrowhead.
This design feature of the present invention allows sufficient slot depth to accommodate as many as six blades generally within the arrowhead body without excessively compromising its strength. Furthermore, it causes the arrowhead to twistingly penetrate game, and with a spinning arrow, drag and turbulence from exposed blade portions is reduced and blade opening is quickened. The arrow rotation during flight is enhanced due to air flow over the shaft body imparting forces upon the exposed portions of the blade and triangular actuating tip.